Various types of watercraft having foils are known in the art. There is shown in U.S. Pat. No. 3,357,389 a hydrofoil system and method of forming lift foils for use therein which is suitable for use with a surface craft. U.S. Pat. No. 3,789,789 describes a hydrofoil sailing craft which has controllable and retractable hydrofoils.
U.S. Pat. No. 4,715,304 to the present inventor describes hydrofoil apparatus comprising a hull, a pair of hydrofoils, each including first and second planar surface portions, pivotal mounting apparatus for mounting the pair hydrofoils onto the hull, and apparatus for selectably and variably determining the dihedral angle between the first and second planar surface portions.